revised fig. 1:shows the 5 µm × 5 µm AFM scans of the MQW samples revealing the surface morphology. The QW growth temperature (T), rms roughness (R) and image height (H) are stated on the image. H is the difference in height between the highest and lowest pixels in the image

fig. 2: The density of dislocations against QW growth temperatures for the MQW samples.

Fig. 2 data: data set for Fig. 2

fig. 3: CL images of the MQW sample taken from the surface. The QW growth temperature (T) is stated on the image.

fig. 4: (a) CL image taken on the sample grown at 698 °C and (b) SE image taken on the same position of (a). Example dislocations are enclosed in the red circles and an example dark patch is highlighted by the yellow curve.

revised fig. 5: (a) The peak emission amplitude and The peak emission amplitude and (b) the peak emission wavelength obtained from a CL line scan performed on the sample grown at 698 °C across a dark patch boundary. Two fitting examples of the dark patch and the bright area are show in (c) and (d), respectively. The dark patch boundary is marked by the green lines. There are two large blue-shift peaks within the dark patch which are related with nearby dislocations. Disregarding the regions near TDs, the average emission amplitudes and wavelengths of the dark patch and the bright area are indicated by red dotted lines.

Fig. 5 data: data set for Fig. 5

fig. 6: (a) The CL image taken in step 2. The line-scan position is highlighted by the yellow line. (b) The AFM profile corresponding to the line-scan position extracted from the AFM image taken in step 4. (c) The overview STEM HAADF image taken in step 6. Dislocations in (c) are matching with the dislocation pits found in (b). The dark patch boundary found in step 3 is marked by thicker Pt deposition on the sample surface, which is highlighted by the green arrow.

Fig. 6 profile: data set for Fig. 6(b)

fig. 7: STEM HAADF images showing the MQW structure of the dark patch and the bright area in the sample grown at 698 °C. The bright lines show the positions of QWs. GWWFs are marked in red doted boxes.

revised fig. 8 The average densities of GWWFs plotted against the QW growth temperatures

Fig. 8 data: data set for Fig. 8